Exemplary embodiments of the present invention relates to a multi-screen video reproducing system suitable for a video reproducing device in a multi-screen display having a large screen. Further, exemplary embodiments provide a video reproducing method in the multi-screen video reproducing system, a timing server and a rendering unit used in the multi-screen video reproducing system, and a display device constituting the multi-screen display.
FIG. 23 is a diagram for describing a multi-screen display. A multi-screen display D is a display constituting one large screen by assembling a plurality of display devices D1 to D4, such as a monitor or projector, as shown in FIG. 17. A multi-screen video reproducing system is a video reproducing device for outputting the video signal input to the respective display devices D1 to D4 of the multi-screen display D.
In the related art, the multi-screen video reproducing system converts a video signal corresponding to a large screen (video signal corresponding to an original video) into each video signal corresponding to each of the display devices D1 to D4 (video signal corresponding to each unit video) through a scan converter so that the converted video signal is input to each of the display device D1 to D4, thereby addressing or achieving the large screen display.
In the related art, the video signal has been digitized. As a result, also in the multi-screen video reproducing system, a demand that the video signal should be handled in the form of the digital signal has increased.
However, when the video signal is handled in the form of the digital signal, the video signal is not automatically synchronized between the display devices D1 to D4, differently from the case of using the scan converter. Therefore, it is required to provide a synchronized reproducing device in order to synchronize the video signal.
Specifically, when the synchronized reproducing device is provided, since the video signal can be synchronized between the display devices D1 to D4, unit video displayed by the respective display devices can be reproduced at an accurate timing and smooth and natural video can be reproduced on the screen as a whole, as shown in FIG. 24A. To the contrary, when the synchronized reproducing device is not provided, since the video signal can not be synchronized between the display devices D1 to D4, unit video displayed by the respective display devices can not, be reproduced at an accurate timing and smooth and natural video can not be reproduced on the screen as a whole, as shown in FIG. 24B.
Related art document Japanese Unexamined Patent Application Publication No. 2002-369163 and related art document ‘3D Interactive Processor for 3D moving images’ collection of lectured documents, 3D Image Conference 2003, 3D Image Conference 2003 executive committee (2003), PP125-128 disclose the synchronized reproducing device to synchronize a plurality of video displays or synchronize the video and audio.
FIG. 25 is a diagram for describing the synchronized reproducing device disclosed in related art document Japanese Unexamined Patent Application Publication No. 2002-369163. As shown in FIG. 25, when the plurality of video signals (streams) are transmitted through an internet, the synchronized reproducing means disclosed in related art document Japanese Unexamined Patent Application Publication No. 2002-369163 absorbs the variation of time caused by the rush circumference of the network 9 from a transmission side system shown in FIG. 25A to a reception side system shown in FIG. 25B and the difference of processing time required to compress and decompress streams 1 and 2 to thus synchronize the video signals between the display devices.
In other words, the transmission side system appends a time code at the time of being distributed to a plurality of distributed streams to thus transmit them to the network. The reception side system receives the plurality of streams through the plurality of receiving devices 11 and 14 to thus output them as the streams. In addition, the difference between the time code of an absolute reference time at the reception side system and the distribution time code appended to the stream is measured about each output stream. And then, the delay of the output of each stream is controlled such that the difference between the time codes of the streams becomes constant. In this manner, the video signals are synchronized between the display devices.
FIG. 26 is a diagram for describing the synchronized reproducing means disclosed in document ‘moving picture display by three-dimensional interactive processor’ collection of lectured documents, three-dimensional image conference 2003, three-dimensional image conference 2003 executive committee (2003), PP125-128 therein. The synchronized reproducing device disclosed therein connects to a LAN (Local Area Network) a host PC for generating video reproducing timing and a cluster PC (PC 1, PC 2, PC 3, . . . , PC N) for outputting video signals (video 1, video 2, video 3, . . . , video N) to display devices, simultaneously distributes broadcast packets functioning as synchronization signals from the host PC to each PC, and synchronizes the video signals between the display devices, as shown in FIG. 26. As a result, the frame difference between the display devices can be suppressed to be smaller than one frame.
In addition, related art document Japanese Unexamined Patent Application Publication No. 2003-235027 discloses a technology for synchronizing the video signal between the display devices, in addition to related art document Japanese Unexamined Patent Application Publication No. 2002-369163 and related art document Japanese Unexamined Patent Application Publication No. 2003-235027.
According to related art document Japanese Unexamined Patent Application Publication No. 2003-235027, when a plurality of members receive common video data from a distribution server using a plurality of terminal devices and reproduces them, if the difference in reception time is occurred at the respective terminal devices, the difference in the scene which the plurality of members sees through the terminal devices is occurred so that smooth communication can not be addressed or achieved between the members. In order to address or solve the above-mentioned and/or other problems, disclosed is an art to synchronize the video reproduction in the plurality of terminal devices.
According to related art document Japanese Unexamined Patent Application Publication No. 2003-235027, first, the time of the video distribution server and the respective terminal devices are unified by using the time distribution server provided on the network. Next, the video distribution server distributes to the respective terminal devices the multicast packets including information indicating the video data and the distribution time. The respective terminal devices receive the distributed multicast packets, distribute the information of the transmission time and reception time to any one of the terminal devices, and gather the information of the reception time difference into one location. In addition, a maximum transmission delay time is calculated from the information of time, a reproducing timing control section of each terminal device adjusts the reproducing timing of the video data using the time as a reference, and then the synchronization can occur.